Changes in retinal oxygen saturation before and after femtosecond LASIK in adult myopic individuals with anisometropia

This study aimed to investigate the relationship between myopia and retinal vascular oxygen saturation, after accounting for optical factors and individual variations. This was a prospective, observational, single-center study. Adults with anisometropia were included. All the participants underwent femtosecond-assisted laser in situ keratomileusis (FS-LASIK), and before and after the surgery, all the patients underwent the examination of visual acuity, intraocular pressure (IOP), spherical equivalent (SE), average keratometry (K), central corneal thickness, and retinal oximeter. A total of 196 adult patients with myopic anisometropia were enrolled. The SE of the less myopic eyes before surgery was - 3.89 ± 3.24 D, which was significantly higher than that of the more myopic eyes - 6.75 ± 3.10 D (p < 0.001). The retinal arterial oxygen saturation (SaO₂) of the less myopic eyes was 94.08 ± 1.61%, which was significantly higher than that of the more myopic eyes 93.36 ± 1.74% (p = 0.003). After FS-LASIK, the SaO₂ of the less myopic eyes (93.29 ± 1.72%) remained significantly higher than that of the more myopic eyes (92.76 ± 1.83%) (p = 0.038). In the multivariate regression analysis, the postoperative SaO₂ was still significantly negatively correlated with axial length (AL) (B = -0.252, P = 0.009). After excluding optical factors and individual variations, SaO₂ remains negatively correlated with AL. Myopia exerts an optical magnification effect on SaO₂.